We are still getting a vacuum signal in the intake of 1.5"-2" in the upper RPMs. The engine is telling us the 750 is too small even with the stock manifold. We've decided to not go with a bigger carb until we change the manifold.
Is the above an "iron clad rule"? Or is it just a generalization? Just asking because I am thinking back to a long gone project that when it was in the upper rpm range still had a small amount of vacuum showing on the gauge....and always wondered if the truck would have benefited from a bigger carbanator.....
